The following is an html representation of a letter written
by Columbus Flight Watch concerning the lack of a backup altimeter
setting on numerous instrument approach procedures to airports
in the Central Ohio area. However, this affects more airports
than just Central Ohio airports. For more history on this issue,
go to "I'd Rather RAAS."
March 12, 2002
NASA Aviation Safety Reporting System
P.O. Box 189
Moffett Field, CA 94035-9800
The FAA has rendered a decision that can easily lead to an unsafe condition in instrument weather during the approach phase of a flight. Specifically, it has intentionally removed the Remote Alternate Altimeter Setting (RAAS) minima from many Terminal Procedures.
As an example, Columbus Ohio's Bolton Airport (TZR) Terminal Procedures dictate that the pilot shall utilize the altimeter setting as derived from the Bolton AWOS (or as a backup, the altimeter setting from the Bolton ATC tower). However, should the tower be unstaffed (as it is 12 hours each day), and the AWOS be out of service (as it was for two evenings this past weekend due to severe weather), the pilot could be left without the appropriate altimeter setting for executing any of the instrument approach procedures.
The changes made by the FAA affect all of the Terminal Procedures (i.e. the ILS RWY 4, NDB RWY 4, & GPS RWY 4). During such an event, all three of these procedures are considered as NOT AUTHORIZED. (Before the AWOS was certified, it used to be that the pilot would simply utilize the CMH altimeter setting and increase the decision altitude or minimum descent altitude, as appropriate.)
This system wide change can impact operators across the nation adversely. However, we feel that the impact of this change has not been widely publicized, and pilots are likely to obtain a clearance for an instrument approach and descend to an unsafe altitude because they are inadvertently utilizing an inappropriate altimeter setting.
We feel this change needs to be publicized more so the instrument pilot understands the ramifications better. We also feel that it would be much safer, and provide our nation a much more robust system of airports, if the FAA would simply change things back to the way they used to be, and publish RAAS minima for airports like this.
Sincerely,
Members of Columbus Flight Watch, Inc.